A markup annotation: one that marks up the document and can carry an author, a pop-up window, replies and a review state.
public abstract class PdfMarkupAnnotation : PdfAnnotation
ISO 32000-2 §12.5.6.2, Tables 172 and 173. The markup types are those Table 171 marks: text, free text, line, square, circle, polygon, polyline, the text markup types, caret, stamp, ink, file attachment, sound, redaction and projection.
kind:method, kind:property, kind:ctor. Press Esc to clear.CreationDateGets the date and time the annotation was created (CreationDate, PDF 1.5), or null.ExternalDataGets the external data dictionary (ExData, PDF 1.7), such as 3D markup, as stored, or null.InReplyToGets the annotation this one is a reply to or grouped with (IRT, PDF 1.5), or null.IntentGets the intent of the annotation (IT, PDF 1.6), such as FreeTextCallout, or null.PopupGets the pop-up annotation for entering or editing the text (Popup, PDF 1.3), or null.ReplyTypeGets how the annotation relates to InReplyTo (RT, PDF 1.6): a reply (the default) or a group.RichTextGets the rich text shown in the pop-up window (RC, PDF 1.5), as stored (XHTML), or null. Not parsed.SubjectGets or sets the subject of the annotation (Subj, PDF 1.5), or null; setting null removes it.TitleGets or sets the text label of the pop-up window's title bar, by convention the author (T, PDF 1.1), or null; setting null removes it.